Sound recording apparatus



Oct. 27, 1931.

E. R. VINSON SOUND RECORDING APPARATUS Filed June l5. 1929 2 Sheets-Sham E. R. Vl N SON Oct. 27, 1931.

SOUND RECORDING APPARATUS Filed June l5. 1929 2 Sheets-Sheet IIIIIIIIIIIIIIII g1/mentor' ELL/@TT f?. I//fvso/v. 35% QN/zeg ,6M/aw,

IIS() Patented Oct. 27, 1931 PATENT OFFICE ELLIOTTYR. 'VINSON, l0F COTTAGE GROVE, OREGON i SOUND :RECORDING APPARATUS Application led June 15, 1929. Serial No. 371,289.

This invention relates to electro-magnetic apparatus for the recording of sound upon moving-picture film, and particularly to improveme-nts in the light-valve apparatus for electrically recording sound variations upon a lm negative bythe variable area method in which variations in sound are recorded by variations in the area of a uniformly dark line `exposed upon the film.

The object of the invention is the .provision of a light-valve of simpleJ construction wherein a shutter is operatively connected with an electro-magnet to vibrate in the major-.axis of a light-slit through which the exposure of the ilm is made in response to current alternations amplified from the microphone and superimposed upon the magnetizing current. 4Thus sound is recorded upon the lilm by the oscillations ofthe shutter or .lightvalve exposing an area or light-track of more or less width but of uniform density as to light, appearing as a heavy line having one `jagged edge denoting the sound variations.

The invention vconsists in the novel construction, adaptation andV arrangement of a light-valve as applied to the electrical recording of sound as will be hereinafter described and claimed.

The accompanying drawings illustrate by way of example an embodiment of my invention in simplified but operative form, in which:

Figure 1 is a view in vertical section of sound recording apparatus constructed in yaccordance with my invention.

Fig. 2 is a view in vertical section taken on line 2-2 of Fig. 1.

Fig. 3 is a partial cross-sectional view on line 3-3 of Fig. 1.

' Fig. 4 is a detached view in front elevation of the hinged panel in which the light exposure slit is formed and upon which the shutter mechanism therefor is mounted.

Fig. 5 is a detached `view in side elevation, partly broken away, and upon an enlarged scale, of a portion of the hinged panel showing in detail the electro-magnetic vibrating and shutter devices.

Fig. 6 is a fragmentary view in vertical section of the panel taken through the eX- posure slit.

Referring to said views, the reference numeral 1 indicates a casing of rectangular form secured to and dependent from a moving-picture camera, indicated at 2. Similarly, the take-up magazine 3 in which the eX- posed iilm 5 is received is disposed below said casing. The casing is provided with a double partition 6, 6 to form a compartment 7 in which a ribbon-ilament electric-lamp 8 is;

installed. In the spaced partitions 6, 6 the lenses 10 and 11 .are mounted to focus the light from said lamp upon the light-slit, as will be hereinafter described.

A partition further divides the interior the wall 15 alter they have passed throughv the film whereby the recording of sound upon the ilm may be audibly monitored in a well known manner.

Sprocket-roller 21 is mounted in the lower portion of the camera 2 and a similar roller 22 in the compartment 16 is positioned adj acent the bottom of the partition 15. Said rollers are driven in unison by suitable connective mechanism, not expressly shown, to actuate the vfilm continuously and smoothly past the light aperture and in step with the intermittent feed apparatus of the camera.

An opening is made in the side of the .casing closed by door-sections 23 and 24 hingedly connected to the casing at 25 and c onnected together by a hinge-point 26. 27 is a latch to secure the door-sections in closed condition. A panel 28 is rigidly mounted on the door-section 23 to extend in parallel fspaced relation from the partitionl when the door is closed and to swing away there-vv from when the door is opened to admitof the film being readily threaded through the casing. Oppositely disposed pairs of resilient pads 30 are mounted uponthe opposing faces of the panel and partition, respectively, betweenwhich the film is lightly engaged, said pads being disposed to contact` with t-he film in line V'with the sprocket-holes 3l thereof. v

Mounted upon thefpanel 28 is an electromagnetic device 32 including a vibratorplate 33 disposed in a plane at right angles to the magnetic field of the electro-magnet.

The output terminal wires 350i the-audio' amplifier, not shown, through which the variations in the electric current from the microphone, not shown, are strengthened are connected to the binding-posts 36 and 37=mounty ed upon the door-section 24 and thencethe current is conveyed throughwires 38 and 39 to the respective pole windings .of the electromagnet where the amplifier'output is" superimposedfupon ,theY magnetizing lcurrent to actuate the vibrator in accordance with 'the frequency of the current vibrations'.

The panel 28 is formed with a light-slit 40 of approximately .0625 in. in length disposed ltransversely to the y'direction of travel rofthe lm'and approximately .0005 in. in width and which is in register with a photo-'sensitized strip 41 ofV the film called the light-track `iacent and to one side of the picture-'frames 42. A rod.'43 is connected medially of the vibrator-plate 33 and extendsinhorizontal directions through a bore or groove 45 in the slit by an extremely slight distanceto admit of av narrowline of light through the slit when the shutter is inactive. To facilitate the adjustment of such outer yedge of the light-slit relativeto the shutter-notch or the effective end-of the'shutte'r a thin disk 50 is rotatably mounted upon the' rear side of the panel in eccentric relation upon' a spindleA 51 and arranged to be manipulated by a spindlehead 52. It will be seen that by turning the disk in the desired direction the operator may cause its edge to overlie more or less of the outer end of thel slit to provide the desired width of unbroken exposed light-sound record at the base of the broken variable recording.

It will be apparent that the shutter47 is oscillated by direct connection with the vibrator element of the electro-magnet in response to variations in the electric current from the microphone and amplier to expose to the light rays emitted from the lamp 8 a line of variable width upon the film.v 'Ihe undisv turbed shutter-opening, with or without the employment of the adjustment-disk 50, appears on the film as a narrow line.' The width of thisline is causedV to widen with a variation in area in accordance with the variations in the audio vfrequency current-supplied to the vibrator-plate so that the width of such4 `line indicates with reproductive fidelity the variations in sound pitch as controlled by the microphone. 2 vThe-'exposed sound record 53 1will appear upon thepositivelilm as a solid darkbandhaving a jagged or hill-and-'dale edge 55whose' height from the base edge 56 determines thepitch while the extremely fine serrations orindentations along the edgev 55 records 'the' modulations "giving the more .delicate characterization of the Vvoice-or music. The apparatus is simple lin construction and in operation and .throughsuch simplicity ofrstructure and manipulation is particularly well adapted as an" attachment for portable 'moving ,picture cameras and for amateur work. v

Having described my invention, what I claim, is :ef I l. In photo-'recording apparatus, -in combinationwith a film-strip having a photosensitized light-track thereon, and means vfor actuating the film in continuousmovement, of a panel against which said film moves having an exposure-slit extending transversely of and in register with said light-track, a shutterformed with a V-shaped notch at its outer end', said shutter masking said slit and mounted for vibratile movements longitudinally ofthe 'slit to expose portions ofy said light-track,-and electro-magnetic yrneans'for effecting the vibration of said shutter.

2. In photo-recording apparatus, in combination'with a film-strip having a photo-sensitized light-track thereon, and means for ac-y tuating the'film in continuous movement, of

ka panel against which said Elm moves havling lan exposure-slit extending transversely of and'in register with said light-track, an eccentrically mounted disc on said panel arrangedto adj ustably limit the opening of said slit, a shutter formed with a V-shaped notch 'at its outer end, said v'shutter masking said slit and mounted for vibrationlongitudinally of the lslit yto expose portions of said light-track, and electro-magnetic means for effecting the vibration offsaid shutter.

3. In Vphoto-recording apparatus, inv combination with a film-strip having a photo-sen- 5 sitized light-track thereon, and means for ac- 

